The utilization of mechanical tissue fastening instruments, notably, surgical staplers and endo-cutters have been increasing steadily in recent years as a substitute for suturing in joining a tissue, joining and cutting a tissue simultaneously and performing anastomosis of tubular organs belonging to the digestive system in a number of surgical disciplines. Over the years these instruments have proven to provide significant clinical benefits of improved patient outcome in addition to procedural benefits of reduced procedure time and simplified surgical tasks when compared to laborious and time consuming suturing, and related cost savings. In certain types of surgical procedures use of surgical staplers/endo-cutters has become the preferred method of joining a tissue including the bariatric, thoracic and colorectal surgeries.
In order to address the specific needs of various surgical procedures, surgical stapler instruments have been developed and are disclosed in, for example, U.S. Pat. No. 5,040,715 (Green, et. al.); U.S. Pat. No. 5,307,976 (Olson, et. al.); U.S. Pat. No. 5,312,023 (Green, et. al.); U.S. Pat. No. 5,318,221 (Green, et. al.); U.S. Pat. No. 5,326,013 (Green, et. al.); and U.S. Pat. No. 5,332,142 (Robinson, et. al.) which are each herein incorporated by reference. Intraluminal or circular stapler instruments have also been developed for use in an anastomosis procedure as disclosed, for example, in U.S. Pat. Nos. 5,104,025 and 5,309,927 which are each herein incorporated by reference.
Known surgical stapler instruments include an end effector that simultaneously makes a longitudinal incision in tissue and applies lines of staples on opposing sides of the incision. The end effector includes a pair of opposed jaw members, rotatably engaged with each other about a pivot at the proximal ends of the jaw members, which, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway or a trocar port. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the staple cartridge. The instrument commonly includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil. When a surgical stapler instrument are used on an organ, such as the lung, stomach and intestine, integrity of the deployed staple line is usually checked with a static pressure leak test immediately following the stapling operation whereby the lumen of the stapled tubular organ is inflated with air to a predetermined pressure to look for visible signs of leak, e.g., bubbles from the staple line submerged in saline water.
The static pressure leak test may provide convenient indications for obvious defects in the line of stapled tissue, for example, due to malformed staples or damage to stapled tissue as a result of over-compression of tissue, at the time of stapling operation but not viability of staple line over a long term. Reports of staple line failures are not uncommon and symptoms thereof may present soon after a surgical procedure, for example, air leaks immediately following a high percentage of lung volume reduction surgeries, or several weeks after discharge of patient, for example, delayed complications following sleeve gastrectomy or colectomy. Failure of staple line may result in luminal contents, air in the lung and liquid content in the digestive tract, leaking into bodily cavity potentially causing morbidity prolonging recovery or even mortality. Precise causes of staple line failures have not been thoroughly studied and understood but the factors, associated with technical aspects of the present state of art of surgical stapling, including weakening of stapled tissue due to over-compression, under-compression of tissue, malformation of staples and weakening of stapled tissue at the intersection of two staple lines, etc. are believed to strongly influence quality and clinical outcome of a surgical stapling operation. In some cases a physician is known to “over-sow” or apply stitches across a line of stapled tissue to reinforce the staple line and to guard against potential failure of the staple line but there have been reports of the suture causing tearing of tissue it is meant to protect. Therefore, significant need exists for means to guard against potential staple line failure arising from known technical limitations inherent to the present state of the art of the surgical stapling technology.
It has been proven through clinical experiences that a static pressure leak test immediately following a surgical stapling operation on an organ having a lumen, such as the lung, stomach and colon, does not provide any reliable indicator as to long term viability of a staple line. These organs exert dynamic load significantly varying in magnitude and frequency as well as temporal pattern on a line of stapled tissue thereon as they undergo cyclic, periodic or irregular physiological motions, e.g., breathing (and occasional coughing) in case of the lung and peristaltic motion (and bolus load in the initial meal intake) in case of the digestive tracts. Partly due to complex nature of the physiological organ motions there are no practical ways to study and quantify, on empirical and/or theoretical basis, stresses on the stapled tissue resulting therefrom and their impacts, in short and long term, on the quality and clinical outcome of a stapling operation on these organs. However, those of skill in the art could appreciate qualitatively the potentially damaging effects of various physiological organ motions by examining the following analysis.
The wall tissue of the lung undergoes cyclic distensions during normal breathing cycles, which could exert dynamic tensile stress, on a stapled tissue thereon, of sizable magnitude due to shear size of the lung despite of relatively low pressure in the lumen thereof averaging at a small fraction of the ambient atmospheric pressure. The total number of breathing cycles and in turn, the cyclic dynamic tensile stress loads on the stapled tissue during average length of healing period of the stapled tissue, a few weeks, is in the millions. In addition, during occasional coughing the lumen pressure may reach a considerable fraction of the ambient atmospheric pressure and the peak tensile stress on the stapled tissue resulting from a coughing could be very high again due to a large size of the lung. The cumulative damaging effects of a series of coughing or in the worst case a single coughing may well prove to be catastrophic to the integrity of the stapled tissue already weakened by the staples penetrating there-through. The fact that the luminal content contained by the lung is air, being more lubricious and capable of slipping even through small opening than a liquid, under pressure likely exacerbates the problem evidenced by not so uncommon cases of air leaks following the lung surgeries involving stapling operations.
The wall tissue of the stomach undergoes somewhat periodic distention during peristaltic digestion motion following intake of meal. Although occurrence is less frequent than or as cyclic as breathing, each period of distention during peristaltic motion of the stomach (incidentally that of the colon) and resultant dynamic stress load on a stapled tissue on the organ may last significantly longer than a breathing cycle and its temporal pattern and average/peak magnitude may vary more significantly, particularly in the initial phase of a meal due to the bolus load, than those resulting from normal breathing, if not, coughing. Non-uniformity in the thickness of the stomach wall tissue may lead to uneven distribution over the line of stapled tissue of the dynamic tensile stress load being concentrated more on the thinner portion thereof, which tends to be weaker than the rest as well. Symptoms of staple line failures after the stomach and colon surgeries, such as a sleeve gastrectomy and colectomy, have been observed to show in wide range of timeframe anywhere between during hospital stay and several weeks after patient discharge. A plausible explanation for such phenomena could be presence of slowly progressing underlying causes of the staple line failures including ischemia of a portion of stapled tissue due to over-compression during a stapling operation and mechanical failure due to cumulative tensile stress loads brought on by the organ motion. The present surgical stapler technology has been developed or since evolved with much consideration of the potentially damaging effects of the organ motions on the clinical outcome of surgery involving stapling operation. Neither has ever been any secondary product introduced into the surgical stapler instrument market, which aims specifically to addresses such issues.
Therefore, it is an object of this invention to provide a surgical device to reduce probability of staple line failures due to known technical limitations of the present state of the art of the surgical stapling technology and damaging effects of organ motion.